It can't be attacked until it's health drops under 200 health points. Until then, it can be damaged by mines & caltrops.
It has the ability to randomly change maps.
When it dies, it will change the day. If it can't, then it will drop a day stone.
Name translation (rough): Wretched

Invasion mob
This creature has I glow in the dark perk
Uses approx 500 greater healing potions and poison antidote while fighting
He has random weaknesses, and has a Golden Star Mace, so he can BROD you! Also has a decent chance of dropping a nexus removal stone.
It has a 1/2 chance of dropping day stones.
If it has a day or nexus stone, it is a bit stronger